Anemia in older adults most commonly results from three overlapping causes: nutritional deficiencies (particularly iron, vitamin B12, and folate), chronic diseases that suppress red blood cell production, and unexplained or multifactorial causes that become more prevalent with age. A 75-year-old with kidney disease and poor appetite, for example, may have anemia driven simultaneously by reduced erythropoietin production, inadequate dietary iron, and low-grade inflammation — making it harder to treat than a straightforward single-cause deficiency. This article covers the full range of contributing factors, how they interact, and what warning signs warrant medical attention.
Anemia is not simply a minor inconvenience in this population. In older adults, it is independently associated with cognitive decline, increased fall risk, fatigue, and reduced functional capacity — all of which are particularly consequential for those already managing dementia or early memory loss. Even mild anemia can worsen brain fog, reduce executive function, and accelerate the decline already underway in neurodegenerative conditions. Understanding the root causes is therefore not just a hematology question — it is a brain health question.
Table of Contents
- What Are the Most Common Nutritional Causes of Anemia in Older Adults?
- How Do Chronic Diseases Cause Anemia in the Elderly?
- What Role Does Aging Itself Play — Beyond Disease?
- What Medications Commonly Cause or Worsen Anemia in Older Adults?
- What Gastrointestinal Conditions Drive Anemia and When Is It Dangerous?
- How Does Anemia Affect Cognitive Function and Dementia Risk?
- What Is the Outlook for Anemia Management in Older Adults?
- Conclusion
- Frequently Asked Questions
What Are the Most Common Nutritional Causes of Anemia in Older Adults?
Nutritional deficiencies account for a significant share of anemia cases in older adults, with iron deficiency anemia being the most common type worldwide. In younger people, iron deficiency usually signals blood loss — heavy menstruation or injury. In older adults, the picture is more complex. Poor dietary intake plays a role, but so does reduced gastric acid production (which impairs iron absorption), long-term use of proton pump inhibitors (PPIs), and occult gastrointestinal bleeding from ulcers, polyps, or colorectal cancer. An 80-year-old on daily aspirin for heart disease, for instance, may be losing small amounts of blood from the gut each day without realizing it. Vitamin B12 deficiency is the second major nutritional culprit.
Unlike iron, the issue here is usually absorption rather than intake. A condition called atrophic gastritis — common in older adults — reduces production of intrinsic factor, the protein that enables B12 absorption in the small intestine. Someone eating plenty of meat and dairy can still become profoundly B12-deficient if their stomach no longer produces enough intrinsic factor. B12 deficiency is especially dangerous for brain health because B12 is essential for maintaining the myelin sheath around nerve fibers. Low B12 causes both macrocytic anemia and neurological damage that can mimic or worsen dementia. Folate (vitamin B9) deficiency is less common but still present, particularly in older adults with very poor diets, alcohol use, or those taking medications like methotrexate or phenytoin that interfere with folate metabolism. Both B12 and folate deficiencies produce enlarged, immature red blood cells that cannot carry oxygen efficiently — so the two look similar on a blood smear, which is why testing both simultaneously matters before starting treatment.
How Do Chronic Diseases Cause Anemia in the Elderly?
Anemia of chronic disease (also called anemia of inflammation) is, in fact, the most common form of anemia in hospitalized older adults. It arises when persistent inflammation — from rheumatoid arthritis, chronic kidney disease, heart failure, diabetes, or cancer — triggers the release of cytokines that interfere with iron metabolism and suppress red blood cell production. The body essentially hoards iron in storage cells rather than releasing it for hemoglobin synthesis. Blood tests in these patients often show low serum iron but normal or elevated ferritin, which distinguishes it from simple iron deficiency anemia where ferritin is low. Chronic kidney disease (CKD) deserves special mention. The kidneys produce erythropoietin, the hormone that signals the bone marrow to make red blood cells.
As kidney function declines with age, erythropoietin production drops, and anemia follows. This is sometimes called renal anemia, and it affects a large proportion of people with stage 3 or higher CKD. Treatment with erythropoiesis-stimulating agents (ESAs) is often necessary in this context, but oral iron supplements alone will not resolve the problem. However, a critical warning applies here: treating anemia of chronic disease with iron supplementation when iron stores are already adequate can cause iron overload and tissue damage. This is why the ferritin and transferrin saturation values on a blood panel are so important before prescribing iron. A physician who treats based on hemoglobin alone, without evaluating iron stores, may make things worse. Patients and caregivers should ask specifically whether iron studies were checked before starting any iron therapy.
What Role Does Aging Itself Play — Beyond Disease?
Aging exerts its own direct effects on the blood-forming system, independent of specific diseases. The bone marrow, where red blood cells are produced, becomes less efficient over time. Stem cell activity declines, and the marrow produces fewer cells in response to physiological signals. This baseline reduction in hematopoietic reserve means older adults have less capacity to compensate when any additional stress — illness, surgery, poor nutrition — is placed on the system. There is also a recognized category called “unexplained anemia of the elderly,” which accounts for roughly one-third of anemia cases in people over 65.
These patients have no identifiable nutritional deficiency, no chronic disease explaining their low hemoglobin, and no evidence of blood loss. Current research suggests this category involves age-related changes in stem cell function, low-grade chronic inflammation, and possibly androgenic hormone decline (testosterone supports red blood cell production, and levels fall steadily with age in both men and women). A 70-year-old man with mildly low hemoglobin, normal iron and B12, no kidney disease, and no chronic inflammation may simply be experiencing this age-related drift. For brain health specifically, this form of anemia is particularly insidious because it develops slowly and without obvious cause, meaning it may go undiagnosed or dismissed as “just aging.” Fatigue, slowed thinking, and reduced stamina are attributed to getting older when in fact they reflect a correctable or manageable physiological change. Caregivers of people with dementia should be especially alert to subtle functional declines that might signal worsening anemia rather than disease progression.
What Medications Commonly Cause or Worsen Anemia in Older Adults?
Polypharmacy — the use of multiple medications simultaneously — is nearly universal in older adults, and several drug classes directly cause or contribute to anemia. Nonsteroidal anti-inflammatory drugs (NSAIDs) and aspirin can cause gastrointestinal bleeding over time, leading to iron loss. Proton pump inhibitors, while prescribed to protect the stomach, reduce acid and thereby impair iron and B12 absorption. Metformin, widely used for type 2 diabetes, interferes with B12 absorption in the gut — a fact that is still underappreciated and often not discussed with patients. Chemotherapy drugs cause anemia by directly suppressing bone marrow activity. Immunosuppressants used in autoimmune conditions can have similar effects.
Some antibiotics, when used long-term, affect red blood cell membranes. And anticoagulants like warfarin or direct oral anticoagulants (DOACs) don’t cause anemia directly but can turn minor bleeding — a small ulcer, a hemorrhoid — into a significant blood loss event. The tradeoff in many of these cases is genuine: the medication is necessary to manage a serious condition, and its anemia-causing side effects are accepted as a managed risk rather than a reason to discontinue therapy. The practical implication is that a comprehensive medication review should be part of any anemia workup in an older adult. A geriatric pharmacist or physician performing a medication reconciliation may identify drugs that can be switched, dose-reduced, or supplemented against. For example, a patient on long-term metformin who develops low B12 can simply have B12 injections added to their regimen — there is no need to abandon an otherwise effective diabetes medication.
What Gastrointestinal Conditions Drive Anemia and When Is It Dangerous?
The gastrointestinal tract is both a source of nutrients for red blood cell production and a potential site of blood loss. In older adults, several GI conditions create anemia risk simultaneously. Atrophic gastritis, mentioned earlier in the context of B12 deficiency, also reduces iron absorption. Celiac disease, often undiagnosed until late life, causes malabsorption of iron, folate, and B12 in the small intestine. Inflammatory bowel disease (IBD) causes both malabsorption and chronic blood loss. And colorectal cancer — whose risk rises sharply with age — may present initially as anemia with no other symptoms. This last point warrants emphasis: iron deficiency anemia in an older adult should always raise the question of occult GI blood loss until proven otherwise.
It is not sufficient to prescribe iron supplements and consider the matter resolved. Current guidelines from gastroenterology organizations recommend endoscopic evaluation for adults over 50 presenting with new iron deficiency anemia, particularly men and postmenopausal women, because the baseline risk of colorectal malignancy is high enough that missing it has serious consequences. Anemia, in this context, is a diagnostic signal as much as a symptom. A limitation to keep in mind: endoscopy carries procedural risks in frail older adults, including sedation complications and perforation. The decision to pursue full colonoscopy versus less invasive testing involves a real tradeoff that must be individualized. For a 90-year-old with multiple comorbidities and a life expectancy of one to two years, aggressive investigation of mild anemia may not serve their goals of care. These decisions belong in the context of goals-of-care conversations with the patient, family, and medical team.
How Does Anemia Affect Cognitive Function and Dementia Risk?
The brain is one of the most oxygen-dependent organs in the body. Anemia, by reducing the oxygen-carrying capacity of the blood, directly impairs cerebral oxygenation. In people with already-compromised cerebrovascular function — as is common in vascular dementia and mixed dementia — even mild anemia can precipitate noticeable cognitive changes. A person who has been managing well with early-stage dementia may suddenly appear more confused, more easily fatigued, or less able to manage daily tasks during a period of worsening anemia.
Several longitudinal studies have found that anemia in older adults is associated with a significantly higher risk of developing dementia over time. One large study following adults over 65 found that those who were anemic at baseline had a roughly 41 percent higher risk of developing dementia over the following 3.4 years compared to non-anemic peers. The mechanism is not fully established — it may involve chronic hypoxia, inflammation, vascular changes, or some combination — but the association is consistent enough to be clinically meaningful. For anyone involved in dementia care, treating anemia is not optional or cosmetic; it is part of managing the condition.
What Is the Outlook for Anemia Management in Older Adults?
The prognosis for anemia in older adults depends heavily on its underlying cause. Nutritional deficiencies, when identified and treated, are often reversible — B12 injections produce measurable improvements in hemoglobin and neurological symptoms within weeks. Anemia from chronic kidney disease can be managed with ESAs and iron to maintain quality of life. Unexplained anemia of the elderly, however, has fewer definitive treatment options, and management focuses largely on monitoring and minimizing contributing factors.
Research into the biology of aging and anemia is ongoing. Studies are exploring the role of inflammatory pathways, hormonal changes, and stem cell senescence as potential therapeutic targets. Newer diagnostic tools are improving the ability to distinguish between anemia subtypes, which matters because treating the wrong cause can delay recovery or cause harm. The key takeaway for caregivers and patients is that anemia in an older adult should never be assumed to be “just normal aging” — it deserves a thorough evaluation and, where possible, targeted treatment.
Conclusion
Anemia in older adults is a common but underappreciated condition with a wide range of causes: nutritional deficiencies in iron, B12, and folate; chronic diseases including kidney disease and inflammatory conditions; medication side effects; gastrointestinal blood loss; and the age-related decline in bone marrow function. These causes frequently overlap, making accurate diagnosis essential before treatment begins. For individuals with dementia or cognitive decline, anemia deserves particular attention because reduced cerebral oxygenation can directly worsen cognitive symptoms and accelerate functional decline.
The most important steps for anyone managing an older adult’s health are to ensure anemia is detected through routine blood work, that the cause is properly investigated rather than assumed, and that treatment is matched to the underlying mechanism. If someone in your care has unexplained fatigue, worsening confusion, or reduced stamina, anemia should be near the top of the differential. A complete blood count with iron studies, B12, and folate is a low-cost, low-risk starting point that can meaningfully change the care plan.
Frequently Asked Questions
Is anemia a normal part of aging?
Anemia is common in older adults but not inevitable or normal. While some degree of hematopoietic decline occurs with aging, most anemia cases have identifiable causes that warrant investigation and treatment. Assuming it is simply a consequence of aging risks missing underlying conditions, including cancer or serious nutritional deficiencies.
What blood tests diagnose anemia and its cause in older adults?
A complete blood count (CBC) identifies anemia and red blood cell characteristics. Iron studies (serum iron, ferritin, transferrin saturation) assess iron status. Serum B12 and folate levels screen for nutritional deficiencies. A comprehensive metabolic panel evaluates kidney function. Together, these tests can identify the majority of common anemia causes.
Can anemia cause confusion or worsening dementia symptoms?
Yes. The brain requires a steady oxygen supply, and anemia reduces the blood’s oxygen-carrying capacity. In older adults with existing cognitive impairment, even mild anemia can worsen confusion, fatigue, and daily functioning. Treating anemia in this population has been shown to improve cognitive performance in some cases.
How is anemia treated differently in older adults compared to younger people?
Treatment must account for comorbidities, polypharmacy, and the risks of therapy. Oral iron supplements are often poorly tolerated or poorly absorbed in older adults, making intravenous iron preferable in some cases. B12 injections bypass absorption problems caused by atrophic gastritis. Erythropoiesis-stimulating agents are used for renal anemia but require careful monitoring. Frailty and goals of care also shape how aggressively anemia is treated.
Should anemia in an older adult always be investigated for cancer?
Iron deficiency anemia in adults over 50, particularly in men and postmenopausal women, should prompt evaluation for gastrointestinal blood loss, which may include colorectal cancer. However, the decision to pursue endoscopy must be individualized based on the patient’s overall health, functional status, and goals of care. Not every frail elderly patient will benefit from invasive investigation.
